Method for Feeding Back Channel State Information in Wireless Communication System and Apparatus Therefor

1. A method for transmitting CSI (Channel State Information) by a user equipment in a wireless access system, the method comprising: receiving configuration information including a first codebook subset restriction of a first CSI process and a second codebook subset restriction of a second CSI process; and transmitting the CSI including a RI (Rank Indicator) periodically, based on at least one of the first codebook subset restriction and the second codebook subset restriction, wherein a RI of the second CSI process is the same as a most recently reported RI of the first CSI process, wherein the first codebook subset restriction and the second codebook subset restriction are configured independently, wherein the RI of the second CSI process is restricted to a second RI value set with the second codebook subset restriction, and wherein the second RI value set with the second codebook subset restriction is always the same as a first RI value set with the first codebook subset restriction.

2. The method of claim 1 , wherein the first codebook subset restriction and the second codebook subset restriction are configured as a bitmap parameter.

3. The method of claim 1 , wherein the configuration information is transmitted using RRC (Radio Resource Control) signaling.

4. The method of claim 1 , further comprising: receiving first CSI process configuration information and second CSI process configuration information through RRC (Radio Resource Control) signaling.

5. The method of claim 1 , wherein the CSI includes at least one of the RI, a PMI (Precoding Matrix Indicator), or a CQI (Channel Quality Indicator).

6. A method for receiving CSI (Channel State Information) by a base station in a wireless access system, the method transmitting configuration information including a first codebook subset restriction of a first CSI process and a second codebook subset restriction of a second CSI process; and receiving the CSI including a RI (Rank Indicator) periodically, based on at least one of the first codebook subset restriction information and the second codebook subset restriction information, wherein a RI of the second CSI process is the same as a most recently reported RI of the first CSI process, wherein the first codebook subset restriction and the second codebook subset restriction are configured independently, wherein the RI of the second CSI process is restricted to a second RI value set with the second codebook subset restriction, and wherein the second RI value set with the second codebook subset restriction is always the same as a first RI value set with the first codebook subset restriction.

7. The method of claim 6 , wherein the first codebook subset restriction and the second codebook subset restriction are configured as a bitmap parameter.

8. The method of claim 6 , wherein the first codebook subset restriction and the second codebook subset restriction are transmitted using RRC (Radio Resource Control) signaling.

9. The method of claim 6 , wherein the configuration information is transmitted through RRC (Radio Resource Control) signaling.

10. The method of claim 6 , wherein the CSI includes at least one of the RI, a PMI (Precoding Matrix Indicator), or a CQI (Channel Quality Indicator).

11. A user equipment for transmitting CSI (Channel State Information) in a wireless access system, the user equipment comprising: a RF (Radio Frequency) module; and a processor that controls the RF module to: receive configuration information including a first codebook subset restriction of a first CSI process and a second codebook subset restriction of a second CSI process; and transmit the CSI including a RI (Rank Indicator) periodically, based on at least one of the first codebook subset restriction and the second codebook subset restriction, wherein a RI of the second CSI process is the same as a most recently reported RI of the first CSI process, wherein the first codebook subset restriction and the second codebook subset restriction are configured independently, wherein the RI of the second CSI process is restricted to a second RI value set with the second codebook subset restriction, and wherein the second RI value set with the second codebook subset restriction is always the same as a first RI value set with the first codebook subset restriction.

12. A base station for receiving CSI (Channel State Information) in a wireless access system, the base station comprising: a RF (Radio Frequency) module; and a processor that controls the RF module to: transmit configuration information including a first codebook subset restriction information of a first CSI process and a second codebook subset restriction information of a second CSI process; and receive the CSI including a RI (Rank Indicator) periodically, based on at least one of the first codebook subset restriction information and the second codebook subset restriction information, wherein a RI of the second CSI process is the same as a most recently reported RI of the first CSI process, wherein the first codebook subset restriction and the second codebook subset restriction are configured independently, wherein the RI of the second CSI process is restricted to a second RI value set with the second codebook subset restriction, and wherein the second RI value set with the second codebook subset restriction is always the same as a first RI value set with the first codebook subset restriction.